(1) Field of the Invention
The present invention relates to a file transfer system which transfers a file between a home electric appliance and a personal computer (PC), and in particular relates to a file transfer system which divides a Copy One Generation file that can be copied and transfers the file.
(2) Description of the Related Art
Recently, Internet connections have become widespread in both business and ordinary households due to the development of broadband environments such as xDSL and fiber optics. Moreover, a home network environment in which a consumer PC and home electric appliances are connected via Ethernet™, wireless LAN, and so forth are becoming common. Thus, not only PCs, but also home electric appliances like televisions, DVD recorders, air conditioners, and refrigerators can now be connected to one another.
As one application in the Internet or home network, there is an application for transferring a file between home electric appliances and PCs or the like. For instance, there are examples in which editing is performed by transferring a TV program recorded on the DVD recorder to the PC, a recorded MPEG 2 file is transferred and dubbed between DVD recorders, and so on.
Conventionally, Digital Transmission Content Protection (DTCP) exists as a technique to prevent illegal copying using such a file transfer. In DTCP, “Copy Never,” for prohibiting a copy completely, “Copy One Generation,” for permitting copying of a first generation only, and “Copy Free,” for copying freely, are defined as use permission information (refer to “Digital Transmission Content Protection Specification Volume 1 (Informational Version)”, Hitachi, Ltd, Intel Corporation, Matsushita Electric Industrial Co., Ltd., Sony Corporation, Toshiba Corporation, Revision 1.4, Feb. 28, 2005). In particular, regarding Copy One Generation, transferring a file to another device (the “sink device”) after copying of the first-generation is permitted on the condition that the device in which the file transfer originates (the “source device”) deletes the file or makes it unusable immediately after the transfer. Therefore, since the source device strictly observes this condition for Copy One Generation files, file transfer between the devices can be achieved. After copying of the first generation, the Copy One Generation file is changed to a Copy No More file.